1. Background of the Invention
The present invention relates to a bobbin holding structure to house and hold a bobbin in a bobbin case holder.
2. Description of the Prior Art
FIG. 1 is a perspective view of a typical prior art structure. FIG. 2 is a perspective view of a bobbin 5. FIG. 3 is a perspective view of a bobbin case 6 where the bobbin case 6 is shown partially cut away.
A horizontal axis full rotary looptaker 1 provided in a lock stitch sewing machine includes a rotating hook 3 driven by a rotary shaft 2 to rotate around a horizontal axis and a bobbin case holder 4 housed in the rotating hook 3. Bobbin case 6 housing bobbin 5 fits in the bobbin case holder 4. The bobbin case holder 4 is prevented from rotating by a rotation stopper member 7. When the rotary shaft 2 is rotated, the rotating hook 3 rotates around the rotary axis while the bobbin case holder 4 remains stationary.
FIG. 4 is a perspective view of the horizontal axis full rotary looptaker 1 with the bobbin 5 and the bobbin case 6 removed therefrom. FIG. 5 is a partially enlarged perspective view of the bobbin case 6. With reference made also to FIG. 1 through FIG. 3, a stud 9 projects perpendicularly from a bottom 8 of the bobbin case holder 4 to an open end thereof. As shown in FIG. 3, a hollow shaft 10 of straight cylindrical shape is positioned within the bobbin case 6. The hollow shaft 10 is inserted through a central hole or passage 11 of the bobbin 5, and the bobbin 5 is housed in the bobbin case 6. The bobbin case 6 which houses the bobbin 5 is housed in the bobbin case holder 4 with the stud 9 inserted through the hollow shaft 10.
When the bobbin 5 is within the bobbin case holder 4, a locking piece 13 which is provided on the bobbin case 6 is locked in a locking groove 12 which is formed at a free end of the stud 9, thereby locking the bobbin case 6 in the bobbin case holder 4. Thus, the bobbin 5 is retained in the bobbin case holder 4 by the bobbin case 6. In order to remove bobbin 5 from the bobbin case holder 4, a pivotable flap 14 is operated to release the lock between the locking piece 13 and the stud 9, and the bobbin case 6 then is removed from the bobbin case holder 4 and the bobbin 5 is removed from the bobbin case 6.
In such a prior art structure as described above, it takes substantial time to replace the bobbin, thereby resulting in poor productivity. Moreover, the mechanism for holding the bobbin is complicated.